High acceleration rotary actuator

ABSTRACT

A high acceleration rotary actuator motor assembly is provided comprising a plurality of phase motor elements provided in tandem on a shaft, each phase element including a rotor carrying magnets which alternate exposed poles, the rotor being connected to the shaft and surrounded by a stator formed of a plurality of interconnected segmented stator elements having a contiguous winding to form four magnetic poles, the stator being in electrical communication with a phase electric drive unit, wherein each of the poles exert a magnetic force upon the magnets carried by the rotor when the poles are electrically charged by the phase electric drive unit. The rotors and magnets of each phase motor element are offset about the shaft from one another. In addition, the phase motor elements are electrically isolated from one another.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority as a continuation application of U.S.patent application Ser. No. 13/913,809 filed Jun. 10, 2013, entitledHIGH ACCELERATION ROTARY ACTUATOR, which claims priority from U.S.patent application Ser. No. 13/071,932, filed Mar. 25, 2011, now U.S.Pat. No. 8,482,243, entitled HIGH ACCELERATION ROTARY ACTUATOR, whichclaims priority from U.S. Provisional Application Ser. No. 61/340,948,filed Mar. 25, 2010, entitled HIGH ACCELERATION ROTARY ACTUATOR, thecontents of each of which is hereby incorporated by reference in itsentirety.

FIELD OF THE INVENTION

The present invention relates to a servo motor system. The presentinvention more specifically relates to a multi-phase tandem servo motorassembly for generating high torque at a reduced inertia.

BACKGROUND

Servo motors are generally known in the art. A servo motor is anelectromechanical device in which an electrical input determines amechanical output, for example the rotational velocity and torque of acorresponding motor shaft. A servo motor generally includes a rotorsurrounded by a nonmoving stator. Winding, or coils of wire, arepositioned on the stator. Electrical currents are provided to thewinding, producing a rotating magnetic field. The rotating magneticfield interacts with the rotor, causing the rotor to turn. Theelectrical current is generally provided by a drive. The drive cancontrol the amount of electrical current transmitted to the motor,correspondingly controlling the rotation of the motor shaft. Such drivesmay be referred to as variable-speed or variable-frequency drives.

It is desired for some end uses of a servo motor to have a high torqueto low inertia ratio. A servo motor having a high torque to low inertiaratio provides a fast rate of acceleration of the motor rotor. However,servo motors as described above have limitations on the torque toinertia ratio, especially in applications requiring a larger sizedmotor. This is due to the larger, higher weight motor and componentsnecessary to rotate a rotor at higher speeds or revolutions per minute(RPM).

In addition, it is desired for some end uses of a servo motor to operatewith a higher power density in a smaller overall motor package. A higherpower density provides for an increase in efficiency of the servo motor.However, servo motors as described above have limitations in increasingpower density and efficiency. One reason includes an increase in windingresistance from end turn waste, effectively reducing stator slot fill.End turns of traditionally wound motors do not provide power or torque,but instead generate unnecessary heat, leading to a reduction of motorefficiency. End turns of the servo motors described above are alsosusceptible to heat damage, voltage damage, and insulation breakdown dueto the buildup of heat at the end turns. The end turns are generallysurrounded by air and don't include an adequate thermal path for heat toescape. This can lead to damage to the winding, including a short whichcan render the servo motor inoperable.

Accordingly, an improved servo motor assembly having an improvedelectronic current driving system is provided.

SUMMARY OF THE INVENTION

A high acceleration rotary actuator motor assembly is provided whichcomprises a first phase motor element provided on a shaft, the firstphase element including a first rotor carrying four magnets whichalternate exposed poles, the first rotor being connected to the shaftand surrounded by a first stator formed of a plurality of interconnectedsegmented stator elements having a contiguous winding to form fourmagnetic poles, the first stator being in electrical communication witha first phase electric drive unit, wherein each of the poles exert amagnetic force upon the four magnets carried by the first rotor when thepoles are electrically charged by the first phase electric drive unit. Asecond phase motor element is provided on the shaft a first distancefrom the first phase motor element, the second phase motor elementincluding a second rotor carrying four magnets which alternate exposedpoles, the second rotor being connected to the shaft and surrounded by asecond stator formed of a plurality of interconnected segmented statorelements having a contiguous winding to form four magnetic poles, thesecond stator being in electrical communication with a second phaseelectric drive unit, wherein each of the poles exert a magnetic forceupon the four magnets carried by the second rotor when the poles areelectrically charged by the second phase electric drive unit. A thirdphase motor element is provided on the shaft a second distance from thesecond phase motor element, the third phase motor element including athird rotor carrying four magnets which alternate exposed poles, thethird rotor being connected to the shaft and surrounded by a thirdstator formed of a plurality of interconnected segmented stator elementshaving a contiguous winding to form four magnetic poles, the thirdstator being in electrical communication with a third phase electricdrive unit, wherein each of the poles exert a magnetic force upon thefour magnets carried by the third rotor when the poles are electricallycharged by the third phase electric drive unit. The second rotor andmagnets are offset about the shaft from the first rotor and magnets bythirty degrees of rotation, while the third rotor and magnets beingoffset about the shaft from the first rotor and magnets by sixty degreesof rotation. In addition, the first, second and third phase elements areelectrically isolated from one another.

In another embodiment of a high acceleration rotary actuator motorassembly, the assembly comprises a shaft carrying a first phase motorelement spaced a first distance from a second phase motor element, athird phase motor element spaced a second distance from the second phasemotor element, and a fourth phase motor element spaced a third distancefrom the third phase motor element, each motor element including asquare stator formed of four interconnecting segmented stator elements,each segmented stator element including a longitudinal member and aperpendicular member connected as a unitary element, the longitudinalmember having parallel sides spaced apart by first and second ends, theperpendicular member being orthogonal to the longitudinal member andhaving an arcuate end opposite the longitudinal member, the first enddefines a receiving aperture and the second end includes an attachmentpost, wherein the receiving aperture is adapted to receive the receivingpost of a second segmented stator element and the attachment post isadapted to be received by the receiving aperture of a third segmentedstator element. A four pole winding is provided in each stator of eachphase motor element. A first rotor is connected to the shaft in thefirst phase motor element, a second rotor is connected to the shaft inthe second phase motor element, the second rotor being provided on theshaft π/8 radians offset from the first rotor, a third rotor isconnected to the shaft in the third phase motor element, the third rotorbeing provided on the shaft π/4 radians offset from the first rotor, anda fourth rotor is connected to the shaft in the fourth phase motorelement, the fourth rotor being provided on the shaft 3π/8 radiansoffset from the first rotor.

In another embodiment of a high acceleration rotary actuator motorassembly, the assembly comprises a shaft carrying a first phase motorelement, a second phase motor element, and a third phase motor elementprovided in tandem on the shaft, each motor element including a squarestator formed of four interconnecting segmented stator elements, eachsegmented stator element including a longitudinal member and aperpendicular member connected as a unitary element, the longitudinalmember having parallel sides spaced apart by first and second ends, theperpendicular member being orthogonal to the longitudinal member andhaving an arcuate end opposite the longitudinal member, the first enddefines a receiving aperture and the second end includes an attachmentpost, wherein the receiving aperture is adapted to receive the receivingpost of a second segmented stator element and the attachment post isadapted to be received by the receiving aperture of a third segmentedstator element. A four pole winding is provided in each stator of eachphase motor element. A first rotor is connected to the shaft in thefirst phase motor element, the first rotor carrying four permanentmagnets of a uniform radius and alternating in exposed pole around theshaft. A second rotor is connected to the shaft in the second phasemotor element, the second rotor carrying four permanent magnets of auniform radius and alternating in exposed pole around the shaft, thepermanent magnets of the second rotor being provided on the shaft π/6radians offset from the magnets of the first rotor. A third rotor isconnected to the shaft in the third phase motor element, the third rotorcarrying four permanent magnets of a uniform radius and alternating inexposed pole around the shaft, the permanent magnets of the third rotorbeing provided on the shaft π/3 radians offset from the magnets of thefirst rotor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view according to one or more examples of embodimentsof a high acceleration rotary actuator assembly, showing the rotor andstator assemblies.

FIG. 2 is a cross-sectional view of a section of the high accelerationrotary actuator assembly of FIG. 1, showing a first phase motor elementtaken along line 2-2 of FIG. 1.

FIG. 3 is a graph showing the torque per amp versus rotor angle for onerevolution of the rotor provided in the first phase motor element ofFIG. 2.

FIG. 4 is a cross-sectional view of a section of the high accelerationrotary actuator assembly of FIG. 1, showing a second phase motor elementtaken along line 4-4 of FIG. 1.

FIG. 5 is a graph showing the torque per amp versus rotor angle for onerevolution of the rotor provided in the second phase motor element ofFIG. 4.

FIG. 6 is a cross-sectional view of a section of the high accelerationrotary actuator assembly of FIG. 1, showing a third phase motor elementtaken along line 6-6 of FIG. 1.

FIG. 7 is a graph showing the torque per amp versus rotor angle for onerevolution of the rotor provided in the third phase motor element ofFIG. 6.

FIG. 8 is an overhead plan view of one or more examples of embodimentsof the high acceleration rotary actuator assembly of FIG. 1.

FIG. 9 is an end view of the high acceleration rotary actuator assemblyof FIG. 8 with the end bell removed, showing one or more electronicdrive units in association with the multi-phase tandem rotor servo motorassembly taken along line 9-9 of FIG. 8.

FIG. 10 is a plan view according to one or more examples of embodimentsof a high acceleration rotary actuator assembly, showing the rotor andstator assemblies.

FIG. 11 is a cross-sectional view of a section of the high accelerationrotary actuator assembly of FIG. 10, showing a first phase motor elementtaken along line 11-11 of FIG. 10.

FIG. 12 is a graph showing the torque per amp versus rotor angle for onerevolution of the rotor provided in the first phase motor element ofFIG. 11.

FIG. 13 is a cross-sectional view of a section of the high accelerationrotary actuator assembly of FIG. 10, showing a second phase motorelement taken along line 13-13 of FIG. 10.

FIG. 14 is a graph showing the torque per amp versus rotor angle for onerevolution of the rotor provided in the second phase motor element ofFIG. 13.

FIG. 15 is a cross-sectional view of a section of the high accelerationrotary actuator assembly of FIG. 10, showing a third phase motor elementtaken along line 15-15 of FIG. 10.

FIG. 16 is a graph showing the torque per amp versus rotor angle for onerevolution of the rotor provided in the third phase motor element ofFIG. 15.

FIG. 17 is a cross-sectional view of a section of the high accelerationrotary actuator assembly of FIG. 10, showing a fourth phase motorelement taken along line 17-17 of FIG. 10.

FIG. 18 is a graph showing the torque per amp versus rotor angle for onerevolution of the rotor provided in the fourth phase motor element ofFIG. 17.

FIG. 19 is an elevation view of one or more examples of embodiments of astator element segment used in association with the stator phaseelements of the high acceleration rotary actuator assembly of FIGS. 1and 10.

FIG. 20 is an elevation view of the stator element segment of FIG. 19,showing winding provided on the stator element segment.

FIG. 21 is an elevation view of a portion of one or more examples ofembodiments of the high acceleration rotary actuator assembly of FIG. 1,showing heat conducting elements adapted to extract heat from the statorlamination and winding end turns.

FIG. 22 is an elevation view of a portion of one or more examples ofembodiments of the high acceleration rotary actuator assembly of FIG. 1,showing heat conducting elements having a liquid cooling chamber adaptedto extract heat from the stator lamination and winding end turns.

FIG. 23 is a graph showing the motor torque rating (X-axis) versus thetorque to inertia ratio (Y-axis) comparing commercially available lowinertia servo motors with the high acceleration rotary actuatorassembly.

DETAILED DESCRIPTION

The invention shown in the Figures is generally directed to a highacceleration rotary actuator assembly 100, 200, and in particular amulti-phase tandem rotor servo motor assembly 102 having a plurality ofelectrically isolated phase motor elements 110, 120, 130, 140 formed ofa plurality of segmented stator elements 160 and provided in tandem upona common shaft 104. For ease of discussion and understanding, thefollowing detailed description and illustrations refer to each phaseelement 110, 120, 130, 140 of the multi-phase tandem rotor servo motor102 as a permanent magnet motor. It should be appreciated that apermanent magnet motor is provided for purposes of illustration, andthat the multi-phase tandem rotor servo motor 102 and associated phaseelements 110, 120, 130, 140 disclosed herein may be employed as adifferent type of motor, including, but not limited to, a reluctancemotor or induction motor.

FIG. 1 is a plan view of an embodiment of a high acceleration rotaryactuator assembly 100. The high acceleration rotary actuator assembly100 generally includes a multi-phase tandem rotor servo motor assembly102. The multi-phase tandem rotor servo motor 102 may include aplurality of phases. For example, in the embodiment illustrated in FIG.1, the multi-phase tandem rotor servo motor 102 may include three phaseswhich are separated into three phase motor elements, a first or A phasemotor element 110, a second or B phase motor element 120, and a third orC phase motor element 130. Each phase motor element 110, 120, 130includes a respective input terminal connection or input lead 111, 121,131, which conveys an electrical current to each phase motor element110, 120, 130 from a corresponding electronic drive unit 210, 220, 230(see FIG. 8). Each phase motor element 110, 120, 130 additionallyincludes a respective output terminal connection or output lead 112,122, 132 which conveys an electrical current out of or away from eachphase motor element 110, 120, 130 to a corresponding electronic driveunit 210, 220, 230 (see FIG. 8). The input/output terminal connections111/112, 121/122, 131/132 for each phase motor element 110, 120, 130 areelectrically isolated from one another. In other words, the outputterminal connections 112, 122, 132 are not tied together to form aneutral point. By electrically isolating the terminal connections foreach phase motor element 110, 120, 130, each phase electronic drive unit210, 220, 230 may more readily realize the desired optimum currentwaveform for each respective phase motor element 110, 120, 130. This inturn may assist in the realization of a high torque to inertia ratioservo motor in accordance with the high acceleration rotary actuatorassembly 100 as disclosed herein.

The multi-phase tandem rotor servo motor 102 also includes a lowinertia, common shaft 104. The low inertia shaft 104 has a lower inertiathan shafts or rotors of comparable motors, as shaft 104 has a longerlength and smaller diameter due to the tandem arrangement of the phasemotor elements 110, 120, 130. Each phase motor element 110, 120, 130 ismounted on or connected in tandem to shaft 104. As shown in FIG. 1, whenconnected to shaft 104, each phase motor element 110, 120, 130 may bespaced or separated from one another by a distance 150, 151. Forexample, the first phase motor element 110 may be separated from thesecond stator phase element 120 by a first distance or gap or spacing150. Similarly, the second phase motor element 120 may be separated fromthe third phase motor element 130 by a second distance or gap or spacing151. In one or more examples of embodiments, the phase motor elements110, 120, 130 may be provided in tandem on shaft 104 with minimal to nospacing 150, 151 between the respective phase motor elements 110, 120,130.

The high acceleration rotary actuator assembly 100 of FIG. 1 may alsoinclude end bells 105 (not shown in FIG. 1), a casing or heat shrinktube 106 (not shown in FIG. 1) which encases or surrounds themulti-phase tandem rotor servo motor 102, and one or more bearingassembly 107 (not shown in FIG. 1) which may include a bearing supportor holder 108 and one or more associated bearings 109 (not shown in FIG.1).

FIG. 2 illustrates a cross-sectional view of the first phase motorelement 110. The first phase motor element 110 includes a plurality ofinterconnected stator segments or stator lamination segments orsegmented stator elements 160. As illustrated in FIG. 2, the first phasemotor element 110 includes interconnected stator segments 160 a, 160 b,160 c, 160 d. Each stator segment 160 a, 160 b, 160 c, 160 d is providedapproximately orthogonal to or at an approximate ninety (90) degreeangle to each of the neighboring stator segments 160 a, 160 b, 160 c,160 d. The interconnected stator segments 160 a, 160 b, 160 c, 160 dform an approximately square stator lamination 113. While FIG. 2illustrates the cross-section of a single stator lamination 113, thefirst phase motor element 110 may include a stack or series or pluralityof stator laminations 113. For example, in various embodiments, aplurality of stator laminations 113 may be stacked upon each other toform the first phase motor element 110.

Each stator segment 160 may include a longitudinal member 161 and aperpendicular member 162. Referring to FIG. 2, each of theinterconnected stator segments 160 a, 160 b, 160 c, 160 d respectivelyincludes a longitudinal member or back iron 161 a, 161 b, 161 c, 161 dand a perpendicular member 162 a, 162 b, 162 c, 162 d. The statorlamination 113 and associated longitudinal members or back iron 161 areillustrated in FIG. 2 as arranged in an approximate square shapedconfiguration. An approximate square shaped configuration providesadvantages over standard circular stator lamination and/or back ironarrangements. An approximate square shaped configuration provides agreater or increased amount of back iron 161 in the stator lamination113 than a standard circular stator lamination. This may allow for anincreased amount of conductive material or winding (not shown) to bewound about each stator segment 160. Further, the square shapedconfiguration of the interconnected stator segments 160 allows for alarger slot 114 area. This may allow for an increased amount ofconductive material or winding (not shown) to be wound about each statorsegment 160 and placed in or through slots 114 than a standard circularstator lamination, advantageously reducing heat generation for a giventorque and allowing for a higher torque and torque to inertia ratio.Further, slots 114 may be provided toward the corners of the statorlamination 113, providing for a reduction in heat build-up in the statorlamination 113 due to the improved heat transfer or heat dissipation orcooling. In various embodiments, the stator lamination 113 may berectangular or any other polygonal arrangement which provides for anincreased amount of back iron 161 in the stator lamination 113 than astandard circular stator lamination. Stator lamination 113 may be formedfrom iron, steel, a combination of iron and silicon, silicon steel,metallic alloys, laminates or by any other known and suitable materials,processes or methods.

The interconnected stator segments 160 a, 160 b, 160 c, 160 d define aplurality of slots or winding slots or corner slots 114. Referring toFIG. 2, the illustrated interconnected stator segments 160 a, 160 b, 160c, 160 d define slots 114 a, 114 b, 114 c, 114 d. Each slot 114corresponds with one of four poles of the multi-phase tandem servo motor102. Accordingly, the four slots 114 a, 114 b, 114 c, 114 d define afour pole winding, for example a four pole concentrated winding. Thefour slots 114 a, 114 b, 114 c, 114 d are provided in an arrangementapproximately orthogonal or perpendicular to one another. For example,as shown in FIG. 2, slot 114 a is neighbored by slots 114 b and 114 d,both of which are provided approximately orthogonal to corner slot 114a. Similarly, slot 114 b is neighbored by slots 114 a and 114 c, both ofwhich are provided approximately orthogonal to corner slot 114 b. Slot114 c is neighbored by slots 114 b and 114 d, both of which are providedapproximately orthogonal to corner slot 114 c. Slot 114 d is neighboredby slots 114 c and 114 a, both of which are provided approximatelyorthogonal to corner slot 114 d. To this end, the slots 114 a, 114 b,114 c, 114 d are provided in relation to one another to approximatelyform the corners of a square. Each slot 114 a, 114 b, 114 c, 114 dalternates with its neighboring slot between carrying an electricalcurrent into the slot or carrying an electrical current out of the slotthrough the respective winding (not shown) wound about each statorsegment 160 a, 160 b, 160 c, 160 d. As illustrated in FIG. 2, slots 114a and 114 c carry an electrical current into the respective slots, whichis illustrated by a “+” or plus, while slots 114 b and 114 d carry anelectrical current out of the respective slots, which is illustrated bya “·” or dot. In addition, slot 114 a receives the first input terminalconnection 111, while the first output terminal connection 112 exitsfrom slot 114 b. In one or more examples of embodiments, slots 114 maybe circular, square, rectangular, or any other polygonal arrangement orappropriate size to maximize conductive material or winding inaccordance with the present invention.

The interconnected stator segments 160 a, 160 b, 160 c, 160 d may defineone or more slot necks or slot passages 115. Referring to FIG. 2, eachslot 114 a, 114 b, 114 c, 114 d includes a slot neck 115 a, 115 b, 115c, 115 d. Each slot neck 115 is defined by the perpendicular members 162of the respective interconnected stator segments 160 a, 160 b, 160 c,160 d bordering the respective slot 114. For example, slot neck 115 a isdefined by perpendicular members 162 a, 162 d. Each slot neck 115interconnects the slot 114 and the rotor aperture 116.

The interconnected stator segments 160 a, 160 b, 160 c, 160 d may definea rotor aperture 116. The rotor aperture 116 may be in communicationwith corner slots 114 a, 114 b, 114 c, 114 d, for example, asillustrated in FIG. 2, through slot openings 115 a, 115 b, 115 c, 115 d.In addition, rotor aperture 116 receives or surrounds shaft 104.

Within rotor aperture 116, shaft 104 carries rotor or tandem rotor orfirst rotor 180 a. Mounted upon or connected to rotor 180 a is aplurality of magnets 117. Referring to FIG. 2, rotor 105 a may carryfour magnets 117 a, 117 b, 117 c, 117 d. Magnets 117 a, 117 b, 117 c,117 d are respectively provided about a portion of the circumference ofrotor 180 a. In various embodiments, and as illustrated in FIG. 2, thefour magnets 117 a, 117 b, 117 c, 117 d are each permanent magnets whichare a full 90° (ninety degree) shape. In other words, the four magnets117 a, 117 b, 117 c, 117 d each extend along one-quarter of thecircumference of the rotor 180 a or for 90° (ninety degrees) of theradius of shaft 104 and rotor 180 a. Each neighboring magnet 117 a, 117b, 117 c, 117 d alternates its exposed pole, or pole opposite the rotorside of the magnet, about the circumference of rotor 180 a. For example,magnets 117 a, 117 b, 117 c, 117 d include alternating poles, wheremagnets 117 a and 117 c expose a north pole, which is illustrated by an“N”, while magnets 117 b and 117 d expose a south pole, which isillustrated by an “S”. In addition, magnets 117 a, 117 b, 117 c, 117 dabut or border or communicate with each respective neighboring magnet117. To this end, magnets 117 a, 117 b, 117 c, 117 d have the samethickness radially outward from shaft 104. In other words, magnets 117a, 117 b, 117 c, 117 d have a uniform or a continuous thickness aboutthe circumference of rotor 180 a. The shaft 104, rotor 180 a andassociated magnets 117 a, 117 b, 117 c, 117 d are spaced a distance fromrotor aperture 116 by an air gap 119. The air gap 119 enables the shaft104, rotor 180 a and magnets 117 a, 117 b, 117 c, 117 d to rotateunobstructed within the rotor aperture 116. As observed from thecross-sectional view of FIG. 2, the shaft 104, rotor 180 a and magnets117 a, 117 b, 117 c, 117 d rotate counter-clockwise within rotoraperture 116. In one or more examples of embodiments, magnets 117 mayinclude angled edges, tapered edges, or any suitable edge for operationof the high acceleration rotary actuator assembly 100 in accordance withthe present invention.

FIG. 3 illustrates a graphical representation of the angle of rotationof the rotor, θ_(r) (X-axis) versus the torque per amp (Y-axis) for onerevolution of rotor 180 a about the rotor aperture 116 of the firstphase motor element 110. The torque per amp versus rotor angle of thefirst phase motor element 110 is in the shape of a square or approximatesquare wave. The square wave is generated by the continuous or uniformthickness of magnets 117 about rotor 180 a in air gap 119 of the rotoraperture 116. Based upon the four magnetic poles (or two pole pairs) ofthe first phase motor element 110, the torque per amp versus rotor anglecompletes two electrical cycles for every one revolution or 360°(three-hundred and sixty degrees) of rotation of rotor 180 a. The firstelectrical cycle is completed at 180° (one-hundred and eighty degrees)or π (pie) radians of rotation of rotor 180 a, while the secondelectrical cycle is completed at 360° (three-hundred and sixty degrees)or 2π (two pie) radians of rotation of rotor 180 a.

FIG. 4 illustrates a cross-sectional view of the second phase motorelement 120 of the multi-phase tandem rotor servo motor assembly 102.The second phase motor element 120 includes a plurality ofinterconnected stator segments 160 a, 160 b, 160 c, 160 d, anapproximately square stator lamination 113, a plurality of slots 114,slot necks 115, rotor aperture 116, magnets 117 and air gap 119 whichare substantially as described herein in association with the firstphase motor element 110. Operation and particular components describedherein are substantially the same and like numbers have been used toillustrate the like components. Slot 114 a of the second phase motorelement 120 receives the second input terminal connection 121, while thesecond output terminal connection 122 exits from slot 114 b. Within therotor aperture 116 of the second phase motor element 120, common shaft104 carries rotor 180 b. Mounted upon or connected to rotor 180 b is aplurality of magnets 117. As illustrated in FIG. 4, rotor 180 b carriesfour magnets 117 a, 117 b, 117 c, 117 d. Rotor 180 b and the attachedmagnets 117 a, 117 b, 117 c, 117 d are substantially the same as thosedescribed in association with rotor 180 a, but for the positioning ofrotor 180 b in relation to rotor 180 a on shaft 104. Rotor 180 b isprovided on shaft 104 approximately 30° (thirty degrees) mechanicallylagging from rotor 180 a. In other words, comparing the cross-sectionalview of the first phase motor element 110 of FIG. 2 to thecross-sectional view of the second phase motor element 120 of FIG. 4,rotor 180 b (and the associated magnets 117) is illustrated as offset orrotated from rotor 180 a (and the associated magnets 117) byapproximately 30° (thirty degrees) lagging. Put differently, accordingto the illustrated view of FIG. 4, rotor 180 b (and the associatedmagnets 117) is disposed about shaft 104 approximately 30° (thirtydegrees) in the clockwise direction as compared to rotor 180 a (of FIG.2), as FIGS. 2 and 4 illustrate the rotation of shaft 104 as in thecounter-clockwise direction. In addition to rotor 180 b mechanicallylagging rotor 180 a by approximately 30° (thirty degrees), rotor 180 bhas an electrical angle which is lagging rotor 180 a by approximately60° (sixty degrees). The associated electrical angle of rotor 180 b canbe calculated by multiplying the mechanical angle by N, where N equalsthe number of pole pairs (or one-half the total number of poles).

FIG. 5 illustrates a graphical representation of the angle of rotationof the rotor, θ_(r) (X-axis) versus the torque per amp (Y-axis) for onerevolution of rotor 180 b about the rotor aperture 116 of the secondphase motor element 120. The torque per amp versus rotor angle of thesecond phase motor element 120 is in the shape of a square orapproximate square wave. The square wave is generated by the continuousor uniform thickness of magnets 117 about rotor 180 b in air gap 119 ofthe rotor aperture 116. Based upon the four magnetic poles (or two polepairs) of the second phase motor element 120, the torque per amp versusrotor angle completes two electrical cycles for every one revolution or360° (three-hundred and sixty degrees) of rotation of rotor 180 b. Thefirst electrical cycle is completed at 180° (one-hundred and eightydegrees) or π (pie) radians of rotation of rotor 180 b, while the secondelectrical cycle is completed at 360° (three-hundred and sixty degrees)or 2π (two pie) radians of rotation of rotor 180 b. Comparing torque peramp versus rotor angle of FIG. 5 to FIG. 3, the torque per amp of FIG. 5is shifted 30° (thirty degrees) mechanically lagging to the torque peramp of FIG. 3. In other words, the torque per amp curve of FIG. 5 isshifted π/6 radians to the right as compared to the torque per amp curveof FIG. 3. This is due to rotor 180 b being rotated about shaft 104 30°(thirty degrees) behind, or lagging, rotor 180 a.

FIG. 6 illustrates a cross-sectional view of the third phase motorelement 130 of the multi-phase tandem rotor servo motor assembly 102.The third phase motor element 130 includes a plurality of interconnectedstator segments 160 a, 160 b, 160 c, 160 d, an approximately squarestator lamination 113, a plurality of slots 114, slot necks 115, rotoraperture 116, magnets 117 and air gap 119 which are substantially asdescribed herein in association with the first phase motor element 110.Operation and particular components described herein are substantiallythe same and like numbers have been used to illustrate the likecomponents. Slot 114 a of the third phase motor element 130 receives thethird input terminal connection 131, while the third output terminalconnection 132 exits from slot 114 b. Within the rotor aperture 116 ofthe third phase motor element 130, common shaft 104 carries rotor 180 c.Mounted upon or connected to rotor 180 c is a plurality of magnets 117.As illustrated in FIG. 6, rotor 180 c carries four magnets 117 a, 117 b,117 c, 117 d. Rotor 180 c and the attached magnets 117 a, 117 b, 117 c,117 d are substantially the same as those described in association withrotor 180 a, but for the positioning of rotor 180 c in relation to rotor180 a on shaft 104. Rotor 180 c is provided on shaft 104 approximately60° (sixty degrees) mechanically lagging from rotor 180 a. In otherwords, comparing the cross-sectional view of the first phase motorelement 110 of FIG. 2 to the cross-sectional view of the third phasemotor element 130 of FIG. 6, rotor 180 c (and the associated magnets117) is illustrated as offset or rotated from rotor 180 a (and theassociated magnets 117) by approximately 60° (sixty degrees) lagging.Put differently, according to the illustrated view of FIG. 6, rotor 180c (and the associated magnets 117) is disposed about shaft 104approximately 60° (sixty degrees) in the clockwise direction as comparedto rotor 180 a (of FIG. 2), as FIGS. 2 and 6 illustrate the rotation ofshaft 104 as in the counter-clockwise direction. In addition to rotor180 c mechanically lagging rotor 180 a by approximately 60° (sixtydegrees), rotor 180 c has an electrical angle which is lagging rotor 180a by approximately 120° (one hundred and twenty degrees). The associatedelectrical angle of rotor 180 c can be calculated by multiplying themechanical angle by N, where N equals the number of pole pairs (orone-half the total number of poles).

FIG. 7 illustrates a graphical representation of the angle of rotationof the rotor, θ_(r) (X-axis) versus the torque per amp (Y-axis) for onerevolution of rotor 180 c about the rotor aperture 116 of the thirdphase motor element 130. The torque per amp versus rotor angle of thethird phase motor element 130 is in the shape of a square or approximatesquare wave. The square wave is generated by the continuous or uniformthickness of magnets 117 about rotor 180 c in air gap 119 of the rotoraperture 116. Based upon the four magnetic poles (or two pole pairs) ofthe third phase motor element 130, the torque per amp versus rotor anglecompletes two electrical cycles for every one revolution of rotor 180 c.The first electrical cycle is completed at 180° (one-hundred and eightydegrees) or π (pie) radians of rotation of rotor 180 c, while the secondelectrical cycle is completed at 360° (three-hundred and sixty degrees)or 2π (two pie) radians of rotation of rotor 180 c. Comparing torque peramp versus rotor angle of FIG. 7 to FIG. 3, the torque per amp of FIG. 7is shifted 60° (sixty degrees) mechanically lagging to the torque peramp of FIG. 3. In other words, the torque per amp curve of FIG. 7 isshifted π/3 radians to the right as compared to the torque per amp curveof FIG. 3. This is due to rotor 180 c being rotated about shaft 104 60°(sixty degrees) behind, or lagging, rotor 180 a.

FIG. 8 is an overhead view of one or more examples of embodiments of thehigh acceleration rotary actuator assembly 100. Referring to FIG. 8, thehigh acceleration rotary actuator assembly 100 includes the multi-phasetandem rotor servo motor assembly 102 encased or surrounded by a casingor heat shrink tube 106. Shaft 104 is provided through a portion ofcasing 106. Shaft 104 may include an end 145 adapted to engage orconnect to a drive shaft or other component for the transmission oftorque and/or rotational force from the high acceleration rotaryactuator assembly 100 to a desired assembly, for example a drive train,a pump, or other suitable mechanical assembly. End bells 105, forexample a first end bell 105 a and a second end bell 105 b, may beprovided on either end of shaft 104 and casing 106. Phase motor elements110, 120, 130 may be mounted on or about a portion of shaft 104. Thephase motor elements 110, 120, 130 are substantially as described hereinin association with the phase motor elements 110, 120, 130 illustratedin FIGS. 2-7. Operation and particular components described herein aresubstantially the same and like numbers have been used to illustrate thelike components. The phase motor elements 110, 120, 130 may includewinding (not shown) having winding end turns 171. Rotors 180 a, 180 b,180 c are provided on shaft 104 in association with each respectivephase motor element 110, 120, 130. Each rotor 180 may include magnetassemblies 181, 182. The magnet assemblies 181, 182 may be mounted uponor connected to rotor 180 and each may include a plurality of magnets117. For example, each magnet assembly 181 a/182 a, 181 b/182 b, 181c/182 c may include four magnets 117 a, 117 b, 117 c, 117 d,substantially as described herein in association with the phase motorelements 110, 120, 130 illustrated in FIGS. 2-7.

The multi-phase tandem rotor servo motor assembly 102 may include abearing assembly 107. The bearing assembly 107 may include a bearingholder 108 and a bearing 109. As illustrated in FIG. 8, a plurality ofbearing assemblies 107 are provided on rotor 104, one between each phasemotor element 110, 120, 130 and one on each end of the casing 106 inassociation with end bells 105 a, b. In one or more examples ofembodiments, the multi-phase tandem rotor servo motor assembly 102 mayinclude only a single bearing assembly 107, bearing holder 108 and/orbearing 109. Further, it should be appreciated in one or more examplesof embodiments that the multi-phase tandem rotor servo motor assembly102 may not include any bearing assemblies 107, bearing holders 108and/or bearings 109.

As illustrated in FIG. 8, the high acceleration rotary actuator assembly100 may include a plurality of electronic drive units 210, 220, 230.Each drive unit 210, 220, 230 is respectively in communication with anassociated phase motor element 110, 120, 130 through input/outputterminal connections 111/112, 121/122, 131/132 (see FIG. 1). Each phasemotor element 110, 120, 130 and the associated drive unit 210, 220, 230is electrically isolated from one another. For example, input terminalconnection 111 is in communication with the first or A phase drive unit210 to convey an electrical current of a first phase from the drive unit210 to the first or A phase motor element 110. Output terminalconnection 112 is in communication with drive unit 210 to convey anelectrical current from the first phase motor element 110 to the driveunit 210. Input terminal connection 121 is in communication with secondor B phase drive unit 220 to convey an electrical current of a secondphase from the drive unit 220 to the second or B phase motor element120. Output terminal connection 122 is in communication with drive unit220 to convey an electrical current from the second phase motor element120 to the drive unit 220. Input terminal connection 131 is incommunication with third or C phase drive unit 230 to convey anelectrical current of a third phase from the drive unit 230 to the thirdor C phase motor element 130. Output terminal connection 132 is incommunication with drive unit 230 to convey an electrical current fromthe third phase motor element 130 to the drive unit 230.

Referring to FIG. 9, an end view of one or more examples of embodimentsof the high acceleration rotary actuator assembly 100 is provided withthe end bell 105 a removed illustrating the multi-phase tandem rotorservo motor assembly 102 with shaft 104 there through. The electronicdrive units 210, 220, 230 are provided a distance offset from and incommunication with the multi-phase tandem rotor servo motor assembly 102through input/output terminal connections 111/112, 121/122, 131/132 (notshown, see FIG. 1). In the embodiment illustrated in FIG. 9, casing 106is approximately rectangular with the multi-phase tandem rotor servomotor assembly 102 provided alongside and approximately parallel to theelectronic drive units 210, 220, 230. It should be appreciated thatcasing 106 may be any polygonal shape or arrangement suitable foroperation and use of the high acceleration rotary actuator assembly 100.Further, in one or more examples of embodiments, the electronic driveunits 210, 220, 230 may be provided at an alternative position inrelation to the multi-phase tandem rotor servo motor assembly 102, forexample, including, but not limited to, above, below, at an angle to, orat any other desired position in relation to the multi-phase tandemrotor servo motor assembly 102.

An alternative embodiment of the high acceleration rotary actuatorassembly 200 is shown in FIGS. 10-18. The high acceleration rotaryactuator assembly 200 includes features which are substantially asdescribed herein in association with the high acceleration rotaryactuator assembly 100. Operation and particular components describedherein are substantially the same and like numbers have been used toillustrate the like components. Referring to FIG. 10, in thisembodiment, the multi-phase tandem rotor servo motor assembly 102includes four phases which are separated into four phase motor elements,a first or A phase motor element 110, a second or B phase motor element120, a third or C phase motor element 130 and a fourth or D phase motorelement 140. Each phase motor element 110, 120, 130, 140 is provided onor about rotating shaft 104. Each phase motor element 110, 120, 130, 140includes a respective input terminal connection or input lead 111, 121,131, 141, each of which convey a respective electrical current to therespective phase motor element 110, 120, 130, 140 from a correspondingelectronic drive unit 210, 220, 230, 240 (not shown). Each phase motorelement 110, 120, 130, 140 additionally includes a respective outputterminal connection or output lead 112, 122, 132, 142 which conveys arespective electrical current out of or away from each respective phasemotor element 110, 120, 130, 140 to a corresponding electronic driveunit 210, 220, 230, 240 (not shown). The input/output terminalconnections 111/112, 121/122, 131/132, 141/142 for each phase motorelement 110, 120, 130, 140 are electrically isolated from one another.In other words, the output terminal connections 112, 122, 132, 142 arenot tied together to form a neutral point.

FIG. 11 illustrates a cross-sectional view of the first phase motorelement 110 of the multi-phase tandem rotor servo motor assembly 102 ofthe high acceleration rotary actuator assembly 200. The first phasemotor element 110 includes a plurality of interconnected stator segments160 a, 160 b, 160 c, 160 d, an approximately square stator lamination113, a plurality of slots 114, slot necks 115, rotor aperture 116,magnets 117, air gap 119, shaft 104 and rotor 180 a which aresubstantially as described herein in association with the first phasemotor element 110 illustrated in FIG. 2. Operation and particularcomponents described herein are substantially the same and like numbershave been used to illustrate the like components.

FIG. 12 illustrates a graphical representation of the angle of rotationof the rotor, θ_(r) (X-axis) versus the torque per amp (Y-axis) for onerevolution of rotor 180 a about the rotor aperture 116 of the firstphase motor element 110. The torque per amp versus rotor angle of thefirst phase motor element 110 is in the shape of a square or approximatesquare wave. The square wave is generated by the continuous or uniformthickness of magnets 117 about rotor 180 a in air gap 119 of the rotoraperture 116. Based upon the four magnetic poles (or two pole pairs) ofthe first phase motor element 110, the torque per amp versus rotor anglecompletes two electrical cycles for every one revolution or 360°(three-hundred and sixty degrees) of rotation of rotor 180 a. The firstelectrical cycle is completed at 180° (one-hundred and eighty degrees)or π (pie) radians of rotation of rotor 180 a, while the secondelectrical cycle is completed at 360° (three-hundred and sixty degrees)or 2π (two pie) radians of rotation of rotor 180 a.

FIG. 13 illustrates a cross-sectional view of the second phase motorelement 120 of the multi-phase tandem rotor servo motor assembly 102 ofthe high acceleration rotary actuator assembly 200. The second phasemotor element 120 includes a plurality of interconnected stator segments160 a, 160 b, 160 c, 160 d, an approximately square stator lamination113, a plurality of slots 114, slot necks 115, rotor aperture 116,magnets 117 and air gap 119 which are substantially as described hereinin association with the first phase motor element 110 of FIG. 2.Operation and particular components described herein are substantiallythe same and like numbers have been used to illustrate the likecomponents. Within the rotor aperture 116 of the second phase motorelement 120, common shaft 104 carries rotor 180 b. Mounted upon orconnected to rotor 180 b is a plurality of magnets 117. As illustratedin FIG. 13, rotor 180 b carries four magnets 117 a, 117 b, 117 c, 117 d.Rotor 180 b and the attached magnets 117 a, 117 b, 117 c, 117 d aresubstantially the same as those described in association with rotor 180a, but for the positioning of rotor 180 b in relation to rotor 180 a onshaft 104. Rotor 180 b is provided on shaft 104 approximately 22.5°(twenty-two point five degrees) mechanically lagging from rotor 180 a.In other words, comparing the cross-sectional view of the first phasemotor element 110 of FIG. 11 to the cross-sectional view of the secondphase motor element 120 of FIG. 13, rotor 180 b (and the associatedmagnets 117) is illustrated as offset or rotated from rotor 180 a (andthe associated magnets 117) by approximately 22.5° (twenty-two pointfive degrees) lagging. Put differently, according to the illustratedview of FIG. 13, rotor 180 b (and the associated magnets 117) isdisposed about shaft 104 approximately 22.5° (twenty-two point fivedegrees) in the clockwise direction as compared to rotor 180 a (of FIG.11), as FIGS. 11 and 13 illustrate the rotation of shaft 104 as in thecounter-clockwise direction. In addition to rotor 180 b mechanicallylagging rotor 180 a by approximately 22.5° (twenty-two point fivedegrees), rotor 180 b has an electrical angle which is lagging rotor 180a by approximately 45° (forty five degrees). The associated electricalangle of rotor 180 b can be calculated by multiplying the mechanicalangle by N, where N equals the number of pole pairs (or one-half thetotal number of poles).

FIG. 14 illustrates a graphical representation of the angle of rotationof the rotor, θ_(r) (X-axis) versus the torque per amp (Y-axis) for onerevolution of rotor 180 b about the rotor aperture 116 of the secondphase motor element 120 of FIG. 13. The torque per amp versus rotorangle of the second phase motor element 120 is in the shape of a squareor approximate square wave. The square wave is generated by thecontinuous or uniform thickness of magnets 117 about rotor 180 b in airgap 119 of the rotor aperture 116. Based upon the four magnetic poles(or two pole pairs) of the second phase motor element 120, the torqueper amp versus rotor angle completes two electrical cycles for every onerevolution or 360° (three-hundred and sixty degrees) of rotation ofrotor 180 b. The first electrical cycle is completed at 180°(one-hundred and eighty degrees) or π (pie) radians of rotation of rotor180 b, while the second electrical cycle is completed at 360°(three-hundred and sixty degrees) or 2π (two pie) radians of rotation ofrotor 180 b. Comparing torque per amp versus rotor angle of FIG. 14 toFIG. 12, the torque per amp of FIG. 14 is shifted 22.5° (twenty-twopoint five degrees) mechanically lagging to the torque per amp of FIG.12. In other words, the torque per amp curve of FIG. 14 is shifted π/8radians to the right as compared to the torque per amp curve of FIG. 12.This is due to rotor 180 b being rotated about shaft 104 22.5°(twenty-two point five degrees) behind, or lagging, rotor 180 a.

FIG. 15 illustrates a cross-sectional view of the third phase motorelement 130 of the multi-phase tandem rotor servo motor assembly 102 ofthe high acceleration rotary actuator assembly 200. The third phasemotor element 130 includes a plurality of interconnected stator segments160 a, 160 b, 160 c, 160 d, an approximately square stator lamination113, a plurality of slots 114, slot necks 115, rotor aperture 116,magnets 117 and air gap 119 which are substantially as described hereinin association with the first phase motor element 110 of FIG. 2.Operation and particular components described herein are substantiallythe same and like numbers have been used to illustrate the likecomponents. Within the rotor aperture 116 of the third phase motorelement 130, common shaft 104 carries rotor 180 c. Mounted upon orconnected to rotor 180 c is a plurality of magnets 117. As illustratedin FIG. 15, rotor 180 c carries four magnets 117 a, 117 b, 117 c, 117 d.Rotor 180 c and the attached magnets 117 a, 117 b, 117 c, 117 d aresubstantially the same as those described in association with rotor 180a, but for the positioning of rotor 180 c in relation to rotor 180 a onshaft 104. Rotor 180 c is provided on shaft 104 approximately 45° (fortyfive degrees) mechanically lagging from rotor 180 a. In other words,comparing the cross-sectional view of the first phase motor element 110of FIG. 11 to the cross-sectional view of the third phase motor element130 of FIG. 15, rotor 180 c (and the associated magnets 117) isillustrated as offset or rotated from rotor 180 a (and the associatedmagnets 117) by approximately 45° (forty five degrees) lagging. Putdifferently, according to the illustrated view of FIG. 15, rotor 180 c(and the associated magnets 117) is disposed about shaft 104approximately 45° (forty five degrees) in the clockwise direction ascompared to rotor 180 a (of FIG. 11), as FIGS. 11 and 15 illustrate therotation of shaft 104 as in the counter-clockwise direction. In additionto rotor 180 c mechanically lagging rotor 180 a by approximately 45°(forty five degrees), rotor 180 c has an electrical angle which islagging rotor 180 a by approximately 90° (ninety degrees). Theassociated electrical angle of rotor 180 c can be calculated bymultiplying the mechanical angle by N, where N equals the number of polepairs (or one-half the total number of poles).

FIG. 16 illustrates a graphical representation of the angle of rotationof the rotor, θ_(r) (X-axis) versus the torque per amp (Y-axis) for onerevolution of rotor 180 c about the rotor aperture 116 of the thirdphase motor element 130 of FIG. 15. The torque per amp versus rotorangle of the third phase motor element 130 is in the shape of a squareor approximate square wave. The square wave is generated by thecontinuous or uniform thickness of magnets 117 about rotor 180 c in airgap 119 of the rotor aperture 116. Based upon the four magnetic poles(or two pole pairs) of the third phase motor element 130, the torque peramp versus rotor angle completes two electrical cycles for every onerevolution or 360° (three-hundred and sixty degrees) of rotation ofrotor 180 c. The first electrical cycle is completed at 180°(one-hundred and eighty degrees) or π (pie) radians of rotation of rotor180 c, while the second electrical cycle is completed at 360°(three-hundred and sixty degrees) or 2π (two pie) radians of rotation ofrotor 180 c. Comparing torque per amp versus rotor angle of FIG. 16 toFIG. 12, the torque per amp of FIG. 16 is shifted 45° (forty fivedegrees) mechanically lagging to the torque per amp of FIG. 12. In otherwords, the torque per amp curve of FIG. 16 is shifted π/4 radians to theright as compared to the torque per amp curve of FIG. 12. This is due torotor 180 c being rotated about shaft 104 45° (forty five degrees)behind, or lagging, rotor 180 a.

FIG. 17 illustrates a cross-sectional view of the fourth phase motorelement 140 of the multi-phase tandem rotor servo motor assembly 102 ofthe high acceleration rotary actuator assembly 200. The fourth phasemotor element 140 includes a plurality of interconnected stator segments160 a, 160 b, 160 c, 160 d, an approximately square stator lamination113, a plurality of slots 114, slot necks 115, rotor aperture 116,magnets 117 and air gap 119 which are substantially as described hereinin association with the first phase motor element 110 of FIG. 2.Operation and particular components described herein are substantiallythe same and like numbers have been used to illustrate the likecomponents. Slot 114 a of the fourth phase motor element 140 receivesthe fourth input terminal connection 141, while the second outputterminal connection 142 exits from slot 114 b. Within the rotor aperture116 of the fourth phase motor element 140, common shaft 104 carriesrotor 180 d. Mounted upon or connected to rotor 180 d is a plurality ofmagnets 117. As illustrated in FIG. 4, rotor 180 d carries four magnets117 a, 117 b, 117 c, 117 d. Rotor 180 d and the attached magnets 117 a,117 b, 117 c, 117 d are substantially the same as those described inassociation with rotor 180 a, but for the positioning of rotor 180 d inrelation to rotor 180 a on shaft 104. Rotor 180 d is provided on shaft104 approximately 67.5° (sixty seven point five degrees) mechanicallylagging from rotor 180 a. In other words, comparing the cross-sectionalview of the first phase motor element 110 of FIG. 11 to thecross-sectional view of the fourth phase motor element 140 of FIG. 17,rotor 180 d (and the associated magnets 117) is illustrated as offset orrotated from rotor 180 a (and the associated magnets 117) byapproximately 67.5° (sixty seven point five degrees) lagging. Putdifferently, according to the illustrated view of FIG. 17, rotor 180 d(and the associated magnets 117) is disposed about shaft 104approximately 67.5° (sixty seven point five degrees) in the clockwisedirection as compared to rotor 180 a (of FIG. 11), as FIGS. 11 and 17illustrate the rotation of shaft 104 as in the counter-clockwisedirection. In addition to rotor 180 d mechanically lagging rotor 180 aby approximately 67.5° (sixty seven point five degrees), rotor 180 d hasan electrical angle which is lagging rotor 180 a by approximately 135°(one hundred and thirty five degrees). The associated electrical angleof rotor 180 d can be calculated by multiplying the mechanical angle byN, where N equals the number of pole pairs (or one-half the total numberof poles).

FIG. 18 illustrates a graphical representation of the angle of rotationof the rotor, θ_(r) (X-axis) versus the torque per amp (Y-axis) for onerevolution of rotor 180 d about the rotor aperture 116 of the fourthphase motor element 140 of FIG. 17. The torque per amp versus rotorangle of the fourth phase motor element 140 is in the shape of a squareor approximate square wave. The square wave is generated by thecontinuous or uniform thickness of magnets 117 about rotor 180 d in airgap 119 of the rotor aperture 116. Based upon the four magnetic poles(or two pole pairs) of the fourth phase motor element 140, the torqueper amp versus rotor angle completes two electrical cycles for every onerevolution or 360° (three-hundred and sixty degrees) of rotation ofrotor 180 d. The first electrical cycle is completed at 180°(one-hundred and eighty degrees) or π (pie) radians of rotation of rotor180 d, while the second electrical cycle is completed at 360°(three-hundred and sixty degrees) or 2π (two pie) radians of rotation ofrotor 180 d. Comparing torque per amp versus rotor angle of FIG. 18 toFIG. 12, the torque per amp of FIG. 18 is shifted 67.5° (sixty sevenpoint five degrees) mechanically lagging to the torque per amp of FIG.12. In other words, the torque per amp curve of FIG. 18 is shifted 3π/8radians to the right as compared to the torque per amp curve of FIG. 12.This is due to rotor 180 d being rotated about shaft 104 67.5° (sixtyseven point five degrees) behind, or lagging, rotor 180 a.

It should be appreciated in one or more examples of embodiments that thehigh acceleration rotary actuator assembly 100 may include a few as twophase motor elements or five or more phase motor elements provided intandem on a shaft 104. In one or more examples of embodiments of thehigh acceleration rotary actuator assembly 100 having two phase motorelements, each phase motor element may be substantially as describedherein in association with the first phase motor element 110 of FIG. 2,but for the positioning of the respective rotors 180 on shaft 104. Forexample, the rotors 180 on shaft 104 are offset from one another byapproximately 45° (forty five degrees), wherein one rotor ismechanically lagging the other rotor. Further, the mechanically laggingrotor has an electrical angle which is lagging the other rotor byapproximately 90° (ninety degrees), wherein the electrical angle iscalculated by multiplying the mechanical angle by N, where N equals thenumber of pole pairs (or one-half the total number of poles). Inaddition, in one or more examples of embodiments of the highacceleration rotary actuator assembly 100 having five phase motorelements, each phase motor element may be substantially as describedherein in association with the first phase motor element 110 of FIG. 2,but for the positioning of the respective rotors 180 on shaft 104. Therotors 180 of each successive phase motor element on shaft 104 areoffset from the next successive phase motor element rotor byapproximately 15° (fifteen degrees), wherein each successive phase motorelement rotor is mechanically lagging the previous phase motor elementrotor. Further, each mechanically lagging rotor has an electrical anglewhich is lagging the previous phase motor element rotor by approximately30° (thirty degrees). To this end, in one or more examples ofembodiments, the high acceleration rotary actuator assembly 100 mayinclude X number of phases or phase motor elements provided in tandem ona shaft 104, wherein the offset or mechanical lagging of the rotorsbetween each phase motor element is calculated by 90°/X (ninety degreesdivided by the number of phases or phase motor elements).

FIG. 19 illustrates one or more examples of embodiments of a statorelement segment 160. The stator element segment 160 may include alongitudinal member 161. The longitudinal member 161 may include a firstside 163 opposing a second side 164. In various embodiments, the firstside 163 and second side 164 may be provided substantially parallel toone another. The first and second sides 163, 164 of the longitudinalmember 161 may be spaced apart by a first end 165 and a second end 166.The first and second ends 165, 166 of the longitudinal member 161 may beopposing ends. In various embodiments, the first and second ends 165,166 may be provided at an angle α (alpha) formed between the respectivefirst and second ends 165, 166 and an imaginary line 167 extendingbetween and approximately perpendicular to the first and second sides163, 164 of the longitudinal member 161. For example, as illustrated inFIG. 19, the first and second ends 165, 166 may be provided at an angleα (alpha) which is approximately a 45° (forty five degree) angle betweenthe first and second ends 165, 166 and the imaginary line 167 extendingbetween and approximately perpendicular to the first and second sides163, 164 of the longitudinal member 161. The first and second ends 165,166 may intersect the first side 163 at a first lip 168. As shown inFIG. 19, the first lip 168 may be provided at an angle to the first side163, such that the first lip 168 is rounded or has an angle of curvatureor extends away from the first side 163 toward the second side 164.Further, the first and second ends 165, 166 may intersect the secondside 164 at a second lip 169. As shown in FIG. 19, the second lip 169may be provided at an angle to the second side 164, such that the secondlip 169 is rounded or has an angle of curvature or extends away from thesecond side 164 in a direction away the first side 163. The first end165 may define a receiving aperture or recess 190, while the second end166 may include an attachment post 191. The receiving aperture 190 ofthe first end 165 is adapted to receive an attachment post 191 of asecond end 166. For example, the receiving aperture 190 of the first end165 illustrated in FIG. 19 may receive a corresponding attachment post191 on the second end 166 of another, separate stator element segment160. Similarly, the attachment post 191 of the second end 166illustrated in FIG. 19 may engage or be received by a correspondingreceiving aperture 190 on a first end 165 of another, separate statorelement segment 160. In this way, separate stator element segments 160may engage one another or interconnect to form an approximately squaresegmented stator lamination stack 113, as described in association withphase motor elements 110, 120, 130, 140. The longitudinal member 161 maydefine or include an alignment hole or bolt hole 189. The alignment hole189 may be used to align a plurality of stacked stator element segments160. In addition, the alignment hole 189 may receive a bolt (not shown)to connect a plurality of stacked stator element segments 160 to oneanother or to a respective phase motor element 110, 120, 130, 140.

The stator element segment 160 may also include a perpendicular member162. As illustrated in FIG. 19, the perpendicular member 162 is providedapproximately perpendicular to longitudinal member 161. Theperpendicular member 162 may intersect the longitudinal member 161 atapproximately the mid-point of the longitudinal member 161. In one ormore examples of embodiments, the longitudinal member 161 andperpendicular member 162 are integrally formed or unitary. Further, inone or more examples of embodiments and as illustrated in FIG. 19, thelongitudinal member 161 and perpendicular member 162 may form anapproximate T-shape or are provided in the shape of the letter “T.”

The perpendicular member 162 may include a first border 194 and a secondborder 195. The first and second borders 194, 195 may be providedapproximately parallel to one another. Further, the first and secondborders 194, 195 may be approximately perpendicular to the longitudinalmember 161, first side 163 and second side 164. As shown in FIG. 19, thedistance between the first and second borders 194, 195 may be less thanhalf of the distance between the first and second ends 165, 166, orlength, of longitudinal member 161. The perpendicular member 162 mayalso include an arcuate end 198 opposite the longitudinal member 161.The arcuate end 198 may include a first tooth 199 a and a second tooth199 b. The first tooth 199 a intersects the arcuate end 198 and thefirst border 194, while the second tooth 199 b intersects the arcuateend 198 and the second border 195. It should be appreciated that when aplurality of stator element segments 160 interconnect to form theapproximately square segmented stator lamination stack 113 as describedin association with phase motor elements 110, 120, 130, 140, the arcuateends 198 define the rotor aperture 116, while the second side 164 of thelongitudinal member 161 and the first and second borders 194, 195 of theperpendicular member 162 define slots 114.

FIG. 20 illustrates a stator element segment 160 having winding 170provided thereon. The winding 170 is a single, continuous wire which iswound around the perpendicular member 162 of the stator element segment160. Once a stator element segment 160 has received the desired amountof winding 170, the single, continuous wire is wound around anotherstator element segment 160. Accordingly, a plurality of stator elementsegments 160 are interconnected by winding 170, as the winding 170 isthe same, contiguous wire. To this end, a plurality of stator elementsegments 160 may be wound with winding 170 formed of the same,contiguous wire. The plurality of wound stator element segments 160 maysubsequently be interconnected to form the approximately squaresegmented stator lamination stack 113 as described in association withphase motor elements 110, 120, 130, 140. By winding a complete phasemade of segmented stator elements 160 with a winding 170 of a single,contiguous wire as described herein provides advantages. By using asingle, contiguous wire, potentially unreliable solder joints areexcluded from the winding 170. Further, segmented stator elements 160provides for improved slot fill, as an increased amount of conductorvolume or wire may be placed in the slot, reducing the heat generated inthe winding 170 for a given torque and resulting in a higher torquevalue and an increase in torque to inertia ratio. In addition, anincrease in slot fill reduces end turn waste.

FIG. 21 illustrates a portion of the high acceleration rotary actuatorassembly 100, including the first phase and second phase motor elements110, 120. The phase motor elements 110, 120 include the elementssubstantially as described herein in association with the first phasemotor element 110 illustrated in FIG. 2 and second phase motor element120 illustrated in FIG. 4, including a plurality of interconnectedstator segments 160 a, 160 b, 160 c, 160 d, an approximately squarestator lamination 113, a plurality of slots 114, slot necks 115, rotoraperture 116, magnets 117, air gap 119, shaft 104 and rotor 180.Operation and particular components described herein are substantiallythe same and like numbers have been used to illustrate the likecomponents. Referring to FIG. 21, the motor elements 110, 120 aresurrounded by heat shrunk tube or casing 106. Stator laminations 113have winding which includes winding end turns 171. Heat conductingelements 300 are provided in communication with the stator laminations113 and winding end turns 171 to conduct or remove heat away from therespective stator laminations 113 and winding end turns 171. The heatconducting elements 300 may be formed of a thermally conductiveinsulation compound, for example, but not limited to, aluminum, carbongraphite, a carbon graphite laminate, copper, ceramic, or any otherknown or future developed material suitable to conduct heat away fromthe stator laminations 113 and/or winding end turns 171.

FIG. 22 illustrates a portion of the high acceleration rotary actuatorassembly 100, which is substantially as described herein in associationwith FIG. 21. Operation and particular components described herein aresubstantially the same and like numbers have been used to illustrate thelike components. The heat conducting elements 300 may include a chamber302 adapted to receive a liquid cooling material. The heat conductingelements 300 having a liquid cooling chamber 302 provide for additionalheat extraction from the respective stator laminations 113 and windingend turns 171 than heat conducting elements 300 alone or motors nothaving heat conducting elements 300.

FIG. 23 illustrates a graphical representation of the motor torquerating (X-axis) versus the torque to inertia ratio (Y-axis) comparingservo motors currently commercially available with the high accelerationrotary actuator assembly 100, 200 in accordance with the assembly andassociated advantages disclosed herein. The graph illustrates theincrease in torque to inertia ratio at a motor torque rating of the highacceleration rotary actuator assembly 100, 200 as compared with servomotors currently commercially available.

There are several advantages to the high acceleration rotary actuatorassembly. The high acceleration rotary actuator assembly has a lowinertia rotor and shaft. The shaft has a lower inertia than shafts orrotors of comparable motors, as the shaft has a longer length andsmaller diameter due to the tandem arrangement of the phase motorelements. This provides for less inertia at a given torque thantraditional motors.

In addition, the approximate square shaped configuration of the statorlamination provides advantages over standard circular stator lamination.An approximate square shaped configuration provides a greater amount ofback iron in the stator lamination than a standard circular statorlamination, allowing for an increased amount of conductive material orwinding to be wound about each stator segment. Further, the squareshaped configuration of the stator lamination allows for a larger slotarea, providing for an increased amount of conductive material orwinding to be wound about each stator segment and placed in or throughslots, increasing the slot fill over a standard circular statorlamination. The increased slot fill also advantageously reduces the heatgeneration for a given torque and allows for a higher torque and torqueto inertia ratio. Further, slots may be provided toward the corners ofthe stator lamination, providing for a reduction in heat build-up in thestator lamination due to the improved heat transfer or heat dissipationor cooling.

In addition, the segmented stator formed of segmented stator elementsprovide for a winding with a single, contiguous wire. This eliminatespotential damage to the motor, for example by electrical short, byexcluding unreliable solder joints which are traditionally used toconnect windings. Further, the segmented stator elements provide for animproved slot fill, as an increased amount of winding may be placed inthe slot, reducing the heat generated in the winding for a given torqueand resulting in a higher torque value and an increase in torque toinertia ratio. Further, by increasing slot fill, end turn waste isreduced.

In addition, electrically isolating each of the phase motor elementsprovides for a high torque to inertia ratio. Motors which tie the phaseterminals together to a neutral point incur a restriction in therealization of the optimum current waveform and defeat the electricalisolation of the phases. Electrically isolating each phase motor elementmay assist in the realization of the optimum current waveform.

In addition, the amount of slot liner insulation will be significantlyless than conventional single stator, single rotor multi-phase servomotors. Slot liner insulation is placed inside of a slot to separateconductor wires and avoid a short. By increasing the size of cornerslots, more conductor wires may be placed in each slot. By providingmore room for conductor material in the slots of each of the four poles,and accordingly more conductor wires than insulation in a slot, heat isreduced.

In addition, the four pole arrangement lowers the electrical frequencyat high shaft and rotor speeds than conventional servo motor designsincorporating six or more poles. Conventional servo motors typicallyutilize six or more poles to reduce the back iron and thus reduce thesize of the motor. This results in reducing the rated continuous torqueat higher speeds because of higher iron losses due to higher electricalfrequencies by the increased poles/pole pairs. The four pole squaremulti-phase tandem rotor servo motor assembly does not reduce the ratingof continuous torque at high speeds as much as conventional motordesigns because of the lower frequency iron losses.

In addition, the high acceleration rotary actuator assembly has a betterspeed range than conventional servo motors. At high speeds, conventionalservo motor drives will have to drive the inductance. This requiresextra voltage to drive the inductance proportional to the electricalfrequency. The four pole square tandem servo motor assembly has a lowerelectrical frequency at higher speeds than conventional servo motorsincorporating six poles or more. This advantageously enables the highacceleration rotary actuator assembly to reach a greater maximum speedthan conventional servo motors and accordingly a greater speed range.

Although various representative embodiments of this invention have beendescribed above with a certain degree of particularity, those skilled inthe art could make numerous alterations to the disclosed embodimentswithout departing from the spirit or scope of the inventive subjectmatter set forth in the specification and claims. Joinder references(e.g., attached, coupled, connected) are to be construed broadly and mayinclude intermediate members between a connection of elements andrelative movement between elements. As such, joinder references do notnecessarily infer that two elements are directly connected and in fixedrelation to each other. In some instances, in methodologies directly orindirectly set forth herein, various steps and operations are describedin one possible order of operation, but those skilled in the art willrecognize that steps and operations may be rearranged, replaced, oreliminated without necessarily departing from the spirit and scope ofthe present invention. It is intended that all matter contained in theabove description or shown in the accompanying drawings shall beinterpreted as illustrative only and not limiting. Changes in detail orstructure may be made without departing from the spirit of the inventionas defined in the appended claims.

Although the present invention has been described with reference topreferred embodiments, persons skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention.

What is claimed is:
 1. A high acceleration rotary actuator motorassembly comprising: a first phase motor element provided on a shaft,the first phase element including a first rotor carrying a plurality ofmagnets which alternate exposed poles, the first rotor being connectedto the shaft and surrounded by a first stator formed of a plurality ofinterconnected segmented stator elements having a contiguous winding toform a plurality of magnetic poles; a second phase motor elementprovided on the shaft a first distance from the first phase motorelement, the second phase motor element including a second rotorcarrying a plurality of magnets which alternate exposed poles, thesecond rotor being connected to the shaft and surrounded by a secondstator formed of a plurality of interconnected segmented stator elementshaving a contiguous winding to form a plurality of magnetic poles; athird phase motor element provided on the shaft a second distance fromthe second phase motor element, the third phase motor element includinga third rotor carrying a plurality of magnets which alternate exposedpoles, the third rotor being connected to the shaft and surrounded by athird stator formed of a plurality of interconnected segmented statorelements having a contiguous winding to form a plurality of magneticpoles; the second rotor and magnets being offset about the shaft fromthe first rotor and magnets by thirty degrees of rotation; the thirdrotor and magnets being offset about the shaft from the first rotor andmagnets by sixty degrees of rotation; and the first, second, and thirdphase elements being electrically isolated from one another.
 2. The highacceleration rotary actuator motor assembly of claim 1, wherein themagnets of the first, second and third rotors are permanent magnets. 3.The high acceleration rotary actuator motor assembly of claim 2, whereinthe permanent magnets of the first, second and third rotors each have auniform radius around the shaft.
 4. The high acceleration rotaryactuator motor assembly of claim 1, wherein the cross-section of thestator of the first, second and third phase elements taken in a planeorthogonal to the axis of the shaft is square in shape.
 5. The highacceleration rotary actuator motor assembly of claim 1 wherein thefirst, second and third phase elements each produce a square waveformtorque constant.
 6. The high acceleration rotary actuator motor assemblyof claim 1, wherein the first phase element receives a first phase of athree-phase electric current, the second phase element receives a secondphase of a three-phase electric current, and the third phase elementreceives a third phase of a three-phase electric current.
 7. The highacceleration rotary actuator motor assembly of claim 1, wherein each ofthe segmented stator elements of the first, second and third phase motorelements includes a longitudinal member and a perpendicular memberconnected as a unitary element, the longitudinal member having parallelsides separated by first and second ends, the perpendicular member beingorthogonal to and bisecting the longitudinal member, the perpendicularmember having an arcuate end opposite the longitudinal member, the firstend defines a receiving aperture and the second end includes anattachment post, wherein the receiving aperture is adapted to receivethe receiving post of a second segmented stator element and theattachment post is adapted to be received by the receiving aperture of athird segmented stator element.
 8. The high acceleration rotary actuatormotor assembly of claim 1, wherein the first stator is in electricalcommunication with a first phase of an electric drive unit, the secondstator is in electrical communication with a second phase of theelectric drive unit, and the third stator is in electrical communicationwith a third phase of the electric drive unit.
 9. The high accelerationrotary actuator motor assembly of claim 1, wherein the poles of thefirst stator exert a magnetic force upon the magnets carried by thefirst rotor when the poles are electrically charged by an electric driveunit, the poles of the second stator exert a magnetic force upon themagnets carried by the second rotor when the poles are electricallycharged by the electric drive unit, and the poles of the third statorexert a magnetic force upon the magnets carried by the third rotor whenthe poles are electrically charged by the electric drive unit.
 10. Ahigh acceleration rotary actuator motor assembly comprising: a shaftcarrying a first phase motor element spaced a first distance from asecond phase motor element, a third phase motor element spaced a seconddistance from the second phase motor element, and a fourth phase motorelement spaced a third distance from the third phase motor element; afour pole winding provided in each stator of each phase motor element; afirst rotor connected to the shaft in the first phase motor element; asecond rotor connected to the shaft in the second phase motor element,the second rotor is provided on the shaft π/8 radians offset from thefirst rotor; a third rotor connected to the shaft in the third phasemotor element, the third rotor is provided on the shaft π/4 radiansoffset from the first rotor; and a fourth rotor connected to the shaftin the fourth phase motor element, the fourth rotor is provided on theshaft 3π/8 radians offset from the first rotor.
 11. The highacceleration rotary actuator motor assembly of claim 10, wherein eachmotor element includes a square stator formed of four interconnectingsegmented stator elements, each segmented stator element including alongitudinal member and a perpendicular member connected as a unitaryelement, the longitudinal member having parallel sides spaced apart byfirst and second ends, the perpendicular member being orthogonal to thelongitudinal member and having an arcuate end opposite the longitudinalmember, the first end defines a receiving aperture and the second endincludes an attachment post, wherein the receiving aperture is adaptedto receive the receiving post of a second segmented stator element andthe attachment post is adapted to be received by the receiving apertureof a third segmented stator element
 12. The high acceleration rotaryactuator motor assembly of claim 10, wherein the stators of the first,second, third and fourth first phase motor elements have a squarecross-sectional profile taken perpendicular to the axis of rotation ofthe shaft.
 13. The high acceleration rotary actuator motor assembly ofclaim 10, further comprising: a first electric drive unit in electriccommunication with the first phase motor element; a second electricdrive unit in electric communication with the second phase motorelement; a third electric drive unit in electric communication with thethird phase motor element; and a fourth electric drive unit in electriccommunication with the fourth phase motor element, wherein the first,second, third and fourth phase motor elements are electrically isolatedfrom one another.
 14. The high acceleration rotary actuator motorassembly of claim 10, wherein the first, second, third and fourth rotorseach include a plurality of magnets.
 15. The high acceleration rotaryactuator motor assembly of claim 14, wherein the magnets of the first,second, third and fourth rotors are permanent magnets.
 16. The highacceleration rotary actuator motor assembly of claim 15, wherein thepermanent magnets of the first, second, third and fourth rotors have auniform radius around the shaft.
 17. The high acceleration rotaryactuator motor assembly of claim 15, wherein the first, second, thirdand fourth rotors each have four permanent magnets alternating inexposed pole around the shaft.
 18. The high acceleration rotary actuatormotor assembly of claim 10, wherein the first phase element receives afirst phase of a four-phase electric current, the second phase elementreceives a second phase of the four-phase electric current, the thirdphase element receives a third phase of the four-phase electric current,and the fourth phase element receives a fourth phase of the four-phaseelectric current.
 19. A high acceleration rotary actuator motor assemblycomprising: a shaft carrying a first phase motor element, a second phasemotor element, and a third phase motor element provided in tandem on theshaft; a four pole winding provided in each stator of each phase motorelement; a first rotor connected to the shaft in the first phase motorelement, the first rotor carrying four permanent magnets of a uniformradius and alternating in exposed pole around the shaft; a second rotorconnected to the shaft in the second phase motor element, the secondrotor carrying four permanent magnets of a uniform radius andalternating in exposed pole around the shaft, the permanent magnets ofthe second rotor being provided on the shaft π/6 radians offset from themagnets of the first rotor; and a third rotor connected to the shaft inthe third phase motor element, the third rotor carrying four permanentmagnets of a uniform radius and alternating in exposed pole around theshaft, the permanent magnets of the third rotor being provided on theshaft π/3 radians offset from the magnets of the first rotor.
 20. Thehigh acceleration rotary actuator motor assembly of claim 19, whereineach motor element includes a square stator formed of fourinterconnecting segmented stator elements, each segmented stator elementincluding a longitudinal member and a perpendicular member connected asa unitary element, the longitudinal member having parallel sides spacedapart by first and second ends, the perpendicular member beingorthogonal to the longitudinal member and having an arcuate end oppositethe longitudinal member, the first end defines a receiving aperture andthe second end includes an attachment post, wherein the receivingaperture is adapted to receive the receiving post of a second segmentedstator element and the attachment post is adapted to be received by thereceiving aperture of a third segmented stator element.